How white wine is made

One of the first conditions that should be met in the effort to make good white wine is the correct election of soil, location, and the variety of vine. Generally, it is not recommended to grow Vitis vinifera in the places where normally other plants are grown. This is because the oldest of the domesticated plants requires a really extraordinary care, and many aspects should be taken into account at planting. It includes intensity of solar radiation, mineral composition of soil, climatic conditions not only during summer months, but also in the period of vegetation peace. The optimum humidity of the soil and its ability of self-draining in case of excessive precipitation are important.

Harvesting
The winemaking process begins by harvesting the grapes in September – October – depending on the variety of Vitis vinifera and the maturity. The grapes are picked mechanically or manually. The harvested grapes are put into smaller containers and transported to the distillery for processing. In production of good quality wines, manual harvesting is preferred, in order to avoid damage of the grapes which could ferment and oxide during transport. Upon delivery, the grapes are weighted and the content of sugar is measured by a must meter.

Crushing
Then the grapes are crushed. The crushing machine should crush the grapes so that the seeds and stems are left undamaged. At the same time, they are separated from the crushed berries. If the seeds or stems are damaged, certain substances would be released to the must, which would deteriorate the resulting quality of wine (tannins, etc.). The crushed grapes are called malt residue or pomace.

Fermentation of PomaceIn making white wines, the wine makers may decide whether the pomace will be fermented or immediately pressed. The pomace is put into larger casks or stainless steel tanks, adding sulphur dioxide in order to prevent oxidation and growth of harmful bacteria. Enzymes disturbing the pectins of the pomace and increasing its yield are also added. Fermentation of the pomace lasts for one or two days, depending on the variety of the grape. In fermenting the pomace, aromatic substances from the skins penetrate to the must. Modern technologies allow fermentation of pomace in closed tanks with carbon dioxide in order to prevent intake of air and oxidation. These technologies allow to regulate the temperature in fermentation. For white varieties, the cooling method is often applied. This is because at lower fermentation temperatures, the aromatic substances are not released to the air, but they remain in the must. This method is called cryomaceration.

Pressing
Two basic types of presses exist – pneumatic and hydraulic. Today, mostly pneumatic presses are used. The pressing separates solid substances from liquid ones, in our case the pomace from the must. In this method of pressing, a valuable product is the self-flow, i.e. the must which is released by its own weight, without pressing. Such wines are more delicate and have light flavour. After pressing, the level of sugar is measured by the must meter, the must is further purged by filtration or in a physical way. In the latter case, the sludge is left to settle, and the pure must is pumped into another vessel.

Fermentation
The prepared must is pumped into tanks, adding the yeasts. During fermentation in the tanks, temperature is controlled. The whole process lasts for several days. An important aspect in creating the character of the wine, particularly in northern regions, is the malic – lactic fermentation when the malic acid is transformed into the finer and more pleasant lactic acid. Due to the overall harmonization of sour and sweet flavour, this process requires true professional art of a master wine maker. Upon completion of fermentation, the young wine is carefully pumped into a new vessel (tanks or barrels) so that the sediment composed of lees shall remain in the original tank. The tanks must be filled up to the edge in order to prevent access of the air. The alcohol fermentation in the given manufacturing process lasts for 10 days to 1 month. That period is followed by racking and filtering.